Abstract: An adaptable filtering device and method for filtering sonar signals to remove reverberation signals caused by the vehicle speed and trim and the sea surface and sea bottom. The vehicle itself has an antenna for transmitting and receiving sonar signals, a speed detector, a trim detector, a depth detector, and a distance-to-sea bottom detector and a sonar output device. The present invention forms paths corresponding to each distinct direction from which sonar signals are received by the antenna, each path having a path signal B.sub.i. For each path, a calculation is made to determine a central Doppler-shift frequency .DELTA.f.sub.i and a cut-off frequency f.sub.c.sbsb.i which are to be used to filter the path signal. This calculation is based upon the detected vehicle speed, the detected vehicle trim, the detected vehicle depth, and the detected distance between the vehicle and the sea bottom. The calculated frequencies .DELTA.f.sub.i and f.sub.c.sbsb.